Air driven dental handpieces



y 3, 1966 M. STAUNT 3,248,792

' AIR DRIVEN DENTAL HANDPIECES Filed Aug. 27, 1962 6 SheeosSheet 1 L)INVENTQR. 7 MARTIN STAU NT BY MW ATTORNEY.

May 3, 1966 M. STAUNT AI R DRIVEN DENTAL HANDPIECES 6 Sheets-Sheet 2Filed Aug. 27, 1962 IIIIIIIIIIIII VII,

on, 6,23 III/lull MARTIN STAUNT MW INVENTOR.

ATTORNEY.

May 3, 1966 M. STAUNT AIR DRIVEN DENTAL HANDPIECES 6 Sheets-Sheet 5Filed Aug. 27. 1962 I l-H 3 00 INVENTOR. MARTIN STAUNT ATTORNEYJHIHIIHHHI H Z 722k i l/I y 3, 1966 M. STAUNT 3,248,792

AIR DRIVEN DENTAL HANDPIECES Filed Aug. 27, 1962 6 Sheets-Sheet 4 1N VENTOR. M ARTIN STAU NT BY MW ATTORNEY.

0mm N mmm mww M5 www wwm y 3, 1966 M. STAUNT 3,248,792

AIR DRIVEN DENTAL HANDPIECES Filed Aug. 27, 1962 6 Sheets-Sheet 5INVENTOR.

ATTORNEY.

MARTIN STAUNT y 8, 1966 M. STAUNT 3,248,792

AIR DRIVEN DENTAL HANDPIECES Filed Aug. 27, 1962 5,4 6 Sheets -Sheet 6INVENTOR. fizz/Z22 5Z2azzf BY Qm%%m United States Patent 3,248,792 AIRDRIVEN DENTAL HANDPIECES Martin Staunt, Des Plaines, 111., assignor, bymesne assignments, to American Hospital Supply Corporation, Evanston,11]., a corporation of Illinois Filed Aug. 27, 1962, Ser. No. 219,537 3Claims. (Cl. 32-26) The present application is a continuation-in-part ofmy prior copending application, Serial No. 833,412, filed August 13,1959, now Patent No. 3,050,856 which in turn is continuation-in-part ofapplication Serial No. 494,607, filed March 16, 1955, now abandoned.

The present invention relates to air driven dental hand pieces, and isparticularly concerned with the elimination of the electric motor dentalengine and the drive of dental handpieces of the straight type andvarious attachments which may be attached to the straight handpiece anddriven by means of an air driven turbine.

One of the objects of the invention is the provision of an improved airdriven dental turbine which may be carried by the Wrist joint arm of astraight handpiece so that the drive shaft of the air turbine may beutilized with a belt to drive a straight handpiece and all of theattachments, such as contra angles for cavity preparation at low speeds,contra angles for the cleaning of teeth, and contra angles with amalgamcondensing equipment and grinding attachments.

Another object of the invention is the provision of an improved straighthandpiece assembly including an air driven turbine which may becontrolled by the hand of the operator or by means of a foot control inwhich the speed may be varied from 1,000 r.p.m. to 30,000 rpm. and inwhich the electric dental motor may be eliminated so that the motor cordand engine arm, which are sources of extra weight, noise, and vibration,may be eliminated.

Another object of the invention is the provision of an improved straighthandpiece combination in which gear driven contra angles may be attachedto a straight handpiece which is driven by an air turbine and in whichthe contra angle may be provided with air and water nozzles so that theoperator may have water flowing simultaneously with thet drive air froma nozzle which is carried by the contra angle pointing toward the dentalbur or the water may be shut oil by the operator.

Another object of the invention is the provision of an improved airdriven dental turbine which is so constructed that the air exhaust fromthe turbine may be carried away from the vicinity of the patient to anexhaust vial where more of the lubricant settles at a point remote fromthe patient.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts through the severalviews.

Referring to the drawings, of which there are six sheets, FIG. 1 is aside elevational view of a straight handpiece embodying an air driventurbine by means of which the straight handpiece may have its shaftdriven at all of the speeds which have been formerly accomplished byusing an electric dental engine and a foot control;

FIG. 2 is a fragmentary sectional view of the air driven turbine of FIG.1 taken on the plane of the line 2-2 of FIG. 4;

FIG. 3 is an end view of the threated hose connection taken on the planeof the line 3-3 of FIG. 1;

FIG. 4 is a fragmentary sectional view taken on the plane of the line4-4 of FIG. 2, looking in the direction of the arrows;

FIG. 5 is a sectional View taken on the plane of the line 5-5 of FIG. 2,looking in the direction of the arrows;

FIG. 6 is a sectional view taken on the plane of the line 6-6 of FIG. 2,looking in the direction of the arrows;

FIG. 6a is a fragmentary sectional view taken on the plane of the line6a-6a of FIG. 3, looking in the direction of the arrows;

FIG. 6b is a fragmentary sectional view taken on the axis of the hoseconnector;

FIG. 7 is a fragmentary sectional view taken on the plane of the line7-7 of FIG. 1, looking in the direction plane of the line 7-7 of FIG 1,looking in the direction of the arrows;

FIG. 8b is a fragmentary sectional view taken through the center of ring300 of FIG. 8a;

FIG. is a fragment-arylongitudinal sectional view of an extension unit;

FIG. 9 is a side elevational view in partial section showing theremovable sheath which is adapted to house the mechanism at the lowerend of the straight handpiece of FIG. 7;

FIG. 10 is a view similar to FIG. 1 showing a modified form of airturbine driven straight handpiece which is hand controlled;

FIG. 11 is a fragmentary sectional View taken on the plane of the line11-11 of FIG. 13, looking in the direction of the arrows;

FIG. 12 is an end elevational view taken on the plane of the line 12-12of FIG. 10, looking in the direction of the arrows;

FIG. 13 is a fragmentary sectional view taken on the plane of the line13-13 of FIG. 11, looking in the direction of the arrows;

FIG. 14 is a sectional view taken on the plane of the line 14-14 of FIG.11, looking in the direction of the arrows;

FIG. 15 is a sectional view taken on the plane of the line 15-15 of FIG.11, looking in the direction of the arrows;

FIG. 16 is a sectional view taken on the plane of the line 16-16 of FIG.11, looking in the direction of the arrows;

FIG. 17 is a sectional view taken on the plane of the line 15-15 of FIG.11 with the push button hand control in the right hand position, lookingin the direction of the arrows;

FIG. 18 is a fragmentary sectional view taken on the plane of the line18-18 of FIG. 13, looking in the direction of the arrows;

FIG. 19 is a fragmentary section view passing through the axis of theturbine drive shaft, showing the' construction of the ball bearingsemployed in the turbine;

FIG. 20 is a side elevational view on a larger scale of the plastic ballbearing retainer employed in the ball bearings of FIG. 19;

FIG. '21 is a view in perspective of my straight air driven handpiecewhen equipped with a contra angle for prophylaxis;

FIG. 22 is a similar view of the assembly when equipped with a ballbearing contra angle;

FIG. 23 is a similar view with an amalgam condensing attachment;

Patented May 3, 1966 Y FIG. 24 is a similar view when provided with agrinding Wheel attachment;

FIG. 25 is a similar view of the straight .handpiece assembly which isadapted to be used for low speed high power operations with rotation ineither direction;

REG. 26 is a side elevational view of the rotor of the air driventurbine preferably employed in the turbine of PEG. 1 or FIG. 10;

FIG. 27 is an edge elevational view of the rotor.

Referring to FIGS. l-6, this is an air driven dental handpiececombination adapted to be controlled by a foot controller or a controlcabinet in which the volume and pressure of air is regulated to controlthe speed; and this air driven handpiece is adapted to drive a straighthandpiece assembly and various types of contra angles, further to bedescribed.

Referring to FIG. 1, indicates in its entirety the straight handpieceassembly of the type shown in my prior application Serial No. 833,412filed August 13, 1959, except that the handpiece carries a wrist jointarm 41, comprising a solid curved metal arm which supports a turbinehousing 42 at the end of the arm in position to have the shaft 43 of theturbine connected by a resilient rubber belt 44 to a pulley 45 on thestraight handpiece.

The turbine housing 42 comprises a substantially cylindrical metalhousing except that its outer wall has a slightly concave surface 46.The outer wall is indicated at 47; and it has a cylindrical bore 48which has an open end provided with threads 49 for receiving the threads58 of an end plate 51.

The end plate 51 has sockets 52 for a wrench; and it has an annular flatsurface '53 for engaging the end 54 of the side wall 47. A steppedannular surface 55 engages another annular surface 56 for effecting anair-tight closure. I v

The turbine housing 42 has an inner plane wall 57 opposite to the coverplate; and the inner surface 58 of the cover plate is substantiallyplane, making a cylindrical chamber for receiving a rotor 59.

Referring to FIGS. 19 and 20, these are views of the ball bearingassemblies which are employed at 60 and 61 for rotatably supporting theshaft 43. The same type of ball bearings shown in FIGS. 19 and 20 areemployed everywhere in the handpiece combination. For example, the shaft43 has an outer cylindrical surface and an annular shoulder 62 againstwhich the inner race 63 engages when the inner race is on the shaft.

The inner race has a cylindrical bore 64 and an outer cylindricalsurface 65 and a centrally located circular groove 66 which is formed ona radius larger than the radius of the steel balls 67, giving the ballsa point contact in the grooves 66.

The outer race 68 has an outer cylindrical surface 69 and an innercylindrical surface 70 which is provided with a race groove 71 ofcircular shape formed on a radius, whichagain is of larger size than theradius of the balls 67.

The two races 63 and 68 are accurately located with their grooves 66 and7 1 in alignment, that is, the grooves have the centers of generation onwhich the grooves are formed in alignment with each other.

The outer race is accurately located against an annular shoulder 72formed in the bore 73 of the housing 74 in which the outer race islocated.

The ball bearing assembly is not provided with its full complement ofballs, but a lesser number of balls is employed with the balls spacedfrom each other and held in position by a plastic ball retainer 75. Theball retainer is shown on a larger scale in FIG. 20 in side elevation.

Seven ball sockets are provided with seven balls spaced equally fromeach other about the ball retainer 75. The ball retainer may be made outof nylon, and it comprises a tube of nylon which is slightly shorterthan the races.

The tube has its outer surface 76 spaced from the inner surface 70 ofthe outer race and the tube has its inner surface 77 spaced from theouter surface of the inner race so that the ball retainer is able tofloat between the races without contact except at the balls.

The ball retainer has seven cylindrical ball sockets 78 formed on aradius larger than the balls so that these sockets 78 have only pointcontact with the balls. Each of the seven sockets 78 has a parallelwalled slot 79, 88 extending from the ball socket or bore 78 and at oneend of the ball retainer 75.

The walls 79, 88 of the slots are parallel, but they are closer togetherthan the diameter of the balls so that the walls 79, 88 have to beforced apart to pass the balls into the sockets 78.

The method of assembly of the ball bearing assembly is as follows: Whenthe two races are arranged eccentrically with respect to each other, theraces are spaced from each other at one side sutficiently to insert theballs between the races until seven balls have been gathered in thegrooves at the side opposite to the point of insertion. The balls arethen arranged in equally spaced position in the grooves. Then the ballretainer 75 is placed with the parallel slots 79, 80 registering witheach of the seven balls.

The retainer is then forced axially until the balls pass through theslots 79, 88; and the balls are then located in the sockets 78 and thewalls 79, 88 have again expanded to retain the balls in the sockets 78.

The ball bearings 68 and 61 are of the type shown in FIGS. 19 and 2.0;and the inner race 63 fits on the cylindrical end portion 81 of theshaft 43 against an annular shoulder 82.

The rotor 59 comprises a cylindrical metal member having a cylindricalbore 83 fitting on the enlarged portion of the shaft 43, where it isfrictionally held. The rotor has plane end surfaces 84 and 85 and acylindrical periphery 86, which is interrupted by regularly spacedrectangular slots 87.

The slots 87 are preferably slightly deeper than their width; and eachtooth has its leading corner 88a beveled at 45 degrees in the directionof rotation of the rotor. For example, the slots are 0.045 wide and0.063 deep. As the slots are parallel walled, this means that the teethare wider at the periphery of the rotor. The beveled corners prevent thenext tooth from interfering with the nozzle action on the tooth in frontof the bevel; and it is found-that this bevel improves the torque of theturbine. FIGS. 26 and 27 show the specific shape of the rotor.

Any number of slots may be employed, such as, for example, 24 slots,thus providing the periphery 86 with '24 teeth 88. The rotor 59 isprovided with a short hub 89 at one and extending upwardly intoengagement with the end surface of the adjacent inner race, but clearingthe outer race.

The outer races are frictionally supported in a cylindrical bore 73 ineach end of the housing; and the housing end wall 90 is provided withinner threads 91 for receiving the outer threads on a threaded plug 92.

The threaded plug has an annular flange 93 engaging the outer surface ofthe end wall 90. The threaded plug in each case may have an innerannular surface 94 engaging the end surface of the outer race.

The cover plate 51 is also provided with a cylindrical bore 95 forreceiving the outer race of the bearing assembly 61; and the inner raceis frictionally secured on the cylindrical end 96 of the shaft 43against a spacer sleeve 89a on the rotor.

The cover plate 51 has a threaded bore 97 for receiving the threadedplug 98; and the threaded plug has an annular flange 99 engaging the endof the cover plate. Here again the annular flange 94 on the plug 98engages the outer race at its end surface and clears the inner race.

The shaft has a groove 100 for receiving a split ring 191 inside acavity 102 of the plug 98; and the plug holds the split ring 101 and theshaft against end movement, but the shaft rotates with the inner race,engaging the split ring.

Referring to FIG. 4, the cylindrical bore 48 in the housing 42 has atangential surface 103 at the inlet side and a tangential surface 104 atthe opposite side, forming inlet or outlet conduits 105, 106 between atriangular wall portion 107, 108 and the tangential surface in eachcase.

Either of these outlets 105, 106 may serve as an inlet or outlet; but inFIG. 4 the smaller tube 109 is preferably employed for the inlet,whereas a second tube 110 of larger size may be employed as the exhaustoutlet.

The periphery 86 of the rotor 59 is slightly spaced from the innercylindrical wall 48 so that one conduit 106 serves as a nozzle and theother conduit 105 serves as an outlet.

The housing 42 is welded to the arm 41 at 111 and the housing is alsowelded at 112 to the end of the conduit arm 113, which contains a pairof conduits 114, 115. At the side of the housing where the conduit arm113 is located, the housing is provided with a slot 116 extendingaxially through the side wall and having an L shaped extension 117permitting the exhaust of exhaust air from the side of the rotor aswell.

Referring to FIG. 2, the conduit arm 113 also has an extension 118 orslot in its end opposite the slot 116 communicating with alongitudinally extending conduit 119 which extends to a lateral outlet120 located to register with a peripheral groove 121.

The peripheral groove 121 is covered by a channelled ring 122 having itsopen side inward and having a pair of beveled side Walls 123, 124, theedges 125 of which are located over the peripheral groove 121. The edge123 engages an annular shoulder 126; and the channelled ring 122 slideson the conduit arm 46, where it is retained by a threaded ferrule,further to be described.

The channelled ring 122 has a multiplicity of laterally extending roundholes 127 forexhausting air which passes around the annular space in thegroove 121; but the holes 127 are covered by an inner ring 127a of feltfor absorbing most of the oil which is carried as a mist in the air.

A pin 128 (FIG. 4) is frictionally secured at one side of the groove 121in position topass one of the slots 129, 130 when the channelled ring122 is moved into place; and the tab 131 between the slots may be bentdown to retain the channelled ring 122 in position.

This channelled ring may be removed to replace the felt oil absorbingband inside the channelled ring 122.

Referring to FIG. 4, the conduits 114, 115 are located on an upperplane, as one is shown in dotted lines in FIG. 2; and these conduits1'14, 115 extend to enlarged counterbores 132 and 133, within which apair of stainless steel tubes 110 and 109 are frictionally mounted.

Referring to FIG. 6a, this is a section taken through the conduit arm 13to show the water conduit 135. This water conduit 135 extendslongitudinally of the conduit arm and communicates with a diagonal bore136 at the left end, where a stainless steel water tube 137 isfrictionally secured in the bore 136; and the tube 137 extends over pastthe turbine housing 42, where it is bent downward to extend parallel at138 to the handpiece, where it is provided with ridges 139 for receivinga flexible plastic water tube.

At its opposite end (FIG. 6a) the bore 135 frictionally receives astainless steel water tube 140 which projects from the plane end 141 ofthe conduit arm and extends through a resilient rubber gasket 142, whichhas holes for the two stainless steel air tubes 109, 110 for the watertube 140.

The end of the conduit arm is provided with threads 143 for receiving aferrule 144 of stainless steel having an external ribbed and knurledsurface 145 and an internal 6 threaded bore 146 to be threaded on thethreads 143 of the conduit arm 113. The ferrule 144 has an enlarged bore147 at its end; and it has an annular shoulder 148 at its other end anda reduced cylindrical bore 149 for receiving a stainless steel plug 150,FIG. 6b.

The stainless steel plug 150.has an enlarged annular head 15 1 and anannular shoulder 152 engaging the annular shoulder 148; and the plug hasa reduced cylindrical surface 153 for sliding in the bore 149. The plug150 has three cylindrical bores 154, 155, and 156 for fitting theprojecting tubes 109, 110, and 140, which are the air and water tubesprojecting through the rubber gasket 142; and when the ferrule 144 isthreaded tightly on the threads 143, the plug 150 engages the rubbergasket with its plane end 157 and effects a water-tight and airtightconnection between the plug 150 and the conduit arm 113.

The plug 150 has stainless steel air tubes 158 and 159 and the smallwater tube 160 frictionally mounted in the end of the plug 150 andprovided with external ridges 161 for receiving the air and water hoses162, 163, 164 of flexible plastic which are clamped to the tubes158-160. The hoses are clamped on the ridges 161 of the tubes 158, 159,160 by a brass hose clamp 165.

Referring to FIGS. 2 and 4, the turbine housing has its wall 47 providedwith a through bore 166 within which a stainless steel air tube 167 issecured at a point where it will receive air under pressure from theturbine; and the tube 167 is bent downward to extend along the handpieceat 168, where it is provided with a ribbed end 169 for attachment of aflexible plastic air tube.

The shaft 43 has a clearance in the plug 92 and has its end providedwith a pair of grooves 170, 171; and the grooves are semi-circular incross section for receiving the round resilient rubber belt 44.

The handpiece 40 is provided with a double pulley 45 having a peripheralgroove of large diameter 172 and a peripheral groove 173 of smallerdiameter, these grooves being in alignment, respectively, with thegrooves 171 and 170. The grooves 172, 173 are'semi-circular; and theresilient belt 44 is adapted to stretch to fit the smaller diametergroove 173 and the larger diameter groove 172 to drive the spindle ofthe handpiece 40 at different speeds.

The present air driven turbines are supplied with air under pressurewhich has been filtered, from which the water has been separated, and inwhich lubricant mist has been injected as described in my prior PatentNo. 2,943; 705 on Lubricating Apparatus.

The air containing lubricant mist in the turbine housing is adapted topass through the annular space between the races 63 and 68 around theretainer 75 and around the balls 67, which are constantly lubricated bythe deposit of lubricant thereon. v

The turbine has a clearance around the shaft 43 in the aperture intheplug 92 and the plug 98 may also have a bleeder aperture for passing aircontaining lubricant.

Referring now to FIGS. 10-18, this is a similar air driven turbine 175carried by a wrist arm 41 for driving a straight handpiece 40 by meansof a belt 44.

The present air driven turbine of FIGS. 10-18 is of a type which is handcontrolled, having a push button 176 constituting a valve for turning onthe air under pressure or reversing its direction.

The air driven turbine 175 and the straight handpiece 40 shown in FIGS.10-18 are in every way similar to that shown in FIGS 16a and similarnumerals are applied 7 cylindrical portions 181 and 185 have a slidingfit in the bore 180.

The conduit arm 177 has a centrally located longitudinal bore.186 thatcontains a stainless steel tube 187 having a frictional fit andprotruding from the threaded end 188 of the conduit arm. The tube 187constitutes the inlet for air under pressure containing lubricant mist;and tube 187 protrudes into the transverse bore 180 so that the twoedges 189 and 190 of the tube 187 projecting into the bore 180constitute stops for engaging the tapered portions 182 and 184 of thepush button.

The push button 176 is first inserted into its bore 180; and thereafterthe bore 186 is provided with the tube 187, which acts as a stop forlimiting the motion of the push button in either direction.

The turbine housing 175 has the same transverse slot 116 and L shapedslot 117; but these communicate with a slot 118 and with the bore 191and with a longitudinal bore 192 leading to the annular groove 121,which is covered by the channelled ring 122.

The channelled ring 122 may be exactly similar in construction to thepreceding ring, having a layer of felt 127 for absorbing oil; and thechannelled ring 122 may have a multiplicity of small exhaust holes 193for exhausting the air from the outlet. Some of the air is exhaustedthrough the holes 193; and the balance may be carried back to thecontrol cabinet through a flexible plastic tube from the stainless steeltube 194, which has a frictional fit in the bore 195 extending to theannular groove 121 in the conduit arm 177.

The threaded end 188 of the conduit arm carries a rubber gasket 142; andthe threaded end has the two tubes 194, 187 protruding through therubber gasket and also has a small stainless steel water tube 140 whichextends into a bore 135 as before and communicates with a diagonal bore136 leading to the stainless steel tube 137 for water, which ends at139, where it is to be connected to a plastic water tube.

The turbine is again provided with an air outlet comprising a stainlessair tube 158 which ends at 161 to be connected to a plastic tube.

The same ferrule 144 and stainless steel plug 150 shown in FIG. 6a isused for effecting a connection to the threaded shank 188 of thisconduit arm 177.

The operation of this air driven turbine is substantially the same asthe preceding one in FIGS. 16a except that it may be reversed indirection by means of the push button 176; but the speed of rotation ofthe turbine is controlled by the air pressure, which is regulated at thecontrol cabinet pressure regulator knob.

Referring to FIGS. 1 and 10, the straight handpiece 4% is of the typecovered by my prior applications, Ser. No. 494,607 andSer. No. 833,412,the details of which are shown in FIGS. 7, 8, and 9.

The wrist joint arm 41 in each case is formed with an integral bearinghousing 236, which comprises a cylindrical body extending substantiallyparallel to the shaft 43 of the turbine 42, and having an outer threadedportion 237 at its rear end.

This threaded portion is adapted to receive the internally threadedcollar 238, which has a cylindrical flange 239 internally threaded, andan end flange 240 adapted to engage the outer ball bearing race 241 andsecure it in a counterbore 242 against an annular shoulder 243.

The ball bearing assemblies employed everywhere in the present straighthandpiece are of the type shown in FIGS. 19 and 20, having spaced ballsheld in place by a plastic retainer.

The end flange 240 of the collar has a central bore 244 which has aclearance with respect to the spindle 245 and its spacing sleeve 246 sothat there is no contact between the rotating spindle and the collar238.

The collar 238 has an annular shoulder at 247 for engaging the side oftherace 241 and the end flange 240 has a clearance at 248 beside theraces of the ball bearing to avoid contact between the collar 238 andthe inner race 249.

The races of the ball bearing assembly, indicated at 241 and 24%,comprise hardened steel members; and the inner race 249 comprises anannular member having an inner bore 250 fitting on a reduced portion 251of the spindle 245 against annular shoulder 252.

The inner race has plane end surfaces and an annular groove 253 ofpartially circular cross section in its outer cylindrical surface.

The outer race has an outer cylindrical surface fitting in the bore 242against an annular shoulder 243, and has plane surfaces and an annulargroove of partially circular cross section on its cylindrical surfacefor receiving the balls 254, sufficient of which are provided in thegrooves to extend all theway around the periphery of the grooves with aspacing between the balls.

The cylindrical housing 236 has the enlarged bore 265 and a smallcounterbore 266 and a longer bore 267 in an integral tubular part 268.

The housing 236 has the reduced threaded portion 269 on its left end forreceiving the internally threaded collar 270 which abuts against anannular shoulder 271 and is used to secure the sleeve 272 ofthehandpiece to the wrist joint housing 236.

Tubular part 268 has a cylindrical outer surface 273; and the sleeve 272has a cylindrical bore 274 so that the sleeve may slide on the tube 268against an annular shoulder 275.

The sleeve 272 has a plane end 276 engaging the annular shoulder 275;and the sleeve has a radically projecting annular flange 277, whichextends in to the bore of collar 270 at the clearance 278, where thecollar is unthreaded.

The collar 270 has a smaller counterbore 279 in its left end which isformed with an outer rounded surface; and the bore 79 is adapted toreceive the sleeve 272, which has an outer cylindrical surface 280.

Collar 270 has the inner shoulder 281 which draws the radial flange 277against shoulder 275. There is suflicient clearance between the flange277 and the adjacent surfaces to permit the sleeve 272 to rotate insidethe collar on the tube 268.

Referring to FIG. 8, the sleeve 272 is provided with an annular groove282, which is bounded by two annular shoulders 283, 284, and by acylindrical surface 285 at the bottom of the groove.

This annular groove extends all the way around the sleeve 272, exceptthat sleeve 272 has an axially extending slot 286 extending into its endbeyond the groove 282, and defined by longitudinally extending edges287, 288 which extend to the end 289 of the groove 286, as shown in FIG.8.

This groove 2% provides a longitudinally extending slot into which alongitudinally extending lug 290, carried by the sheath 291 (FIG. 9),may be moved in attaching the sheath.

The circumferential groove 282 about the end of sleeve 272 (FIG. 8a)contains a resilient, partially cylindrical spring band 292, which hassuflicient resiliency so that it can be sprung out of the groove 282 orsprung into the groove 282, as the band is open at its ends 293, 294(FIG. 8a); and the band is of suflicien-t thickness so that it may bewholly housed or received in the groove 282, where it may rotateslidably; and it is used for securing the sheath 291 to the sleeve 272.

Thus the band 292 has the outer and inner cylindrical surfaces 295, 2%(FIG. 8a); and its width is sufficient to fit in the groove 282, havingplane edge surfaces 297, 298 (FIG. 8a). 4 I

Band 292 is of sufiicient external diameter so that it is flush with theoutside of sleeve 272, or the band may project slightly beyond sleeve272 when it is secured in the cylindrical bore 299 of a rotatableactuating member 300,

9 which may be assembled by sliding member 300 on the sleeve 272 andband 292 until it overlaps the sleeve 272 and the sheath 291.

The actuating member 300 is fixedly secured to the band 292 so that itmay be used to rotate the band 292 in groove 286. Band 292 may have apair of oppositely located through bores 301 into which the adjacentparts of the member 300 may be forced with a center punch and brazed bya drop of brazing material.

Thus the band 292 is adapted to be rotated by the actuating member 300,which is actually a tube having the external knurled surfaces 304, 305,separated by a relief 306 and tapering toward both edges.

The band 292 is shorter circumferentially at the groove 282, in which itis mounted, than the adjacent portion of the sleeve 272, as will be seenin FIG. 8b. Thus the ends of the band are at 293, 294, which are widerapart than the edges of the slot 287, 288, and the edges of the groove282, indicated by 283 and 284, are inwardly deformed at 307 and 308 inFIG. 8a, at a point which is spaced from the edge 287 of the slot 286.

This prevents band 292 from making a complete rotation; but it mayrotate across the slot 286, that is, counterclockwise in FIG. 8b, untilthe end 294 of the band 292 completely traverses the slot 286 andstrikes the stop 308. This is the locked position of the band 292.

Band 292 may also rotate in the opposite direction until its end 293engages the stop 308, in which position the ends of the band 202 at 293and 294 will be located outwardly of the ends of the slot 286, which areindicated at 287 and 288. In other words, the band will be completelyout of the slot 286 in its unlocked position.

Referring to FIG. 9, the sheath 291 comprises a tubular metal memberhaving outer cylindrical surfaces at 309 and a grooved gripping surface310, having a plurality of cylindrical knurled lands 311 separated bypartially circular grooves 312.

The grooves being circular makes them easy to keep clean, as foreignparticles do not stick in circular grooves, as they do in rectangularcorners.

At its right end, FIG. 9, the sheath 291 has an enlarged outercylindrical surface 313 and a plane end surface 314, from which thereprojects a partially cylindrical lug or locking extension 290, which isan integral part of the sheath 291.

Lug 290 is bounded at its edges by radially located plane surfaces 315and 316, which surfaces will be received between the edges 287 and 288of the endwise slot 286 in the sleeve 272. In other words, theprojecting extension on the. end of the sheath 291 is complementary tothe slot 286 that is formed for it in the sleeve 272.

The external cylindrical surface 313 of lug 290 is the same size as theexternal surface 280 on sleeve 272, and lug 290 has an internal borewhich is the same size as the bore 267 in sleeve 272.

Lug 290 also has a peripherally extending shallow groove 317, which isof the same size and width as the groove 282 in the sleeve 272 in whichthe band 292 slides. The boundaries of groove 317 may be indicated byits edges 283a and 284a, and its bottom 285a, to indicate that groove317 in the sheath 291 is merely a continuation of the groove 282 in thesleeve 272, when the sheath has its lug 290 in the longitudinally openslot 286.

The end 318 of the sheath 291 (FIG. 9) is plane, fitting against the end319 of the sleeve 272.

The sheath extension 291 forms a part of the straight handpiece which isdriven by the air turbine; but thesheath extension 291 is detachable;and it may be employed to carry any number of attachments further to bedescribed.

The operation of the detachable sheath 291 is as follows:

When the actuating member 300 is rotated until the band 292 slidesrotatably out of the shallow groove 317 in locking extension 290, thesheath 291 may be slid axially away from the sleeve 272 and detached.The unlocking rotating motion of the band 292 is limited by edge 293striking stop 308.

With the parts in this position the same sheath or another sheath may beslid over the spindle and may have its lug slid endwise into theopen-ended slot 2860f the sleeve 272 until the end surfaces 319 ofsleeve 272 and 318 of sheath 291 are in engagement.

Then the edges 315 and 316 of, lug 290 will be engaging the edges 287and 288 of the slot 286 in sleeve 272 to prevent rotation of the sheathon the sleeve.

At this time the shallow groove 317 in the sheath extension 290 willregister with the shallow groove 282 of the sleeve 272, and the lockingband 292 may be rotated by its actuating member 300, the band 292sliding in its present groove 282 and also across the lug 290 in thegroove 317, until the end 294 of band 292 engages stop 308. Then theband 292 locks the extension lug 290 to the sleeve 272; and it is alsoheld in alignment by the inner surface 299 of actuating member 300.

The sheath 291 is also held in accurate concentric alignment with thesleeve 272 by being slidably mounted on the integral tubular part 268,which extends to the left in FIG. 1, from the housing 236 and is adaptedto support the bearing assembly at the tool end of the handpiece.

The tube 268 has the outer cylindrical surface 273, previouslydescribed, engaging the inner bore 274 in sleeve 272, and also engagingthe inner bore 321 in sheath 291.

Thus the sheath 291 and sleeve 272 together constitute a rotatableexternal handle on the handpiece, which, being rotatable on the tube268, permits the wrist joint 225 to hang downward when the sheath 291 issupported by the hand of the user.

The spindle 245 comprises a tubular metal member having the outercylindrical surface at its left end (FIG. 2) extending to the annularshoulder 342. From this point the spindle is enlarged and has the outercylindrical surface 343 provided with a clearance 344 inside the bore321 of the tube 268.

The spindle is supported at its right end by the ball bearing assembly,Where the spindle has a reduced cylindrical surface 251; and the innerrace 249 is held against shoulder 252 by a spacing tube 246 (FIG. 8),which is engaged at its other end by the pulley 346.

Pulley 346 is mounted on a reduced cylindrical portion 347 of thespindle and is held on this reduced portion 347 by a threaded bushing348 having a knurled head 349 with the flat sides for reception of awrench.

The bushing 348 has an annular surface 350 engaging the pulley 346; andthe bushing has an external thread 351 on a reduced portion which isthreaded into a threaded bore 352 in the spindle 245.

The spindle has a key 353 disposed in a keyway in the pulley 346 and thespindle and preventing rotation of the pulley on the spindle. The pulleyis formed with a plurality of peripheral grooves 354 and 355 ofdifferent diameter, separated by radially extending flanges; and thegrooves are tapered for engaging a belt in the form .of a cord whichengages the sides of the pulley, or in some cases engages a curvedbottom of the pulley groove.

The pulley is concave at its inner side 356 so that it extends about thecollar 238 and prevents the ingress of dirt and moisture into the bore244.

The bushing 348, which secures the pulley on the spindle, is alsoprovided with a threaded bore 357 for receiving the threaded portion 358of a chuck actuating rod 359, which extends-through the bore 360 in thespindle 245 and protrudes from the bushing 348, where it is providedwith a metal actuating knob 361, having a threaded bore 362 tightlythreaded on portion 358 and provided with a knurled edge 363.

The knob 361 is adapted to rotate the chuck rod 359 in the bushing 34-8,causing it to engage the collet actuating member 364 by means of its end365. Conversely the rod 359 is adapted to release the chuck by beingmoved to the right.

The rod 359 is guided by a bushing 366, having a tight frictional fit inbore 360 of the spindle 345 to prevent whipping of this end of the rod;and the end surface 365 of the rod is partially spherical.

The spindle 245 is rotatably mounted at its left end by the ballbearings and has the reduced cylindrical part which has a continuationof the bore 360 for housing a collet 367. The bore 360 has afrusto-conical surface 368 at its end which communicates with a smallercounterbore 369; and the spindle has a pair of longitudinal drivingextensions 370, 371 comprising lugs extending longitudinally of thespindle and forming a continuation of the spindle wall from the bore369.

The lugs have flat radially extending sides 372 and a fiat end 373 withbeveled corners, and are intended to be used for driving similar lugs ona driven member 374 (FIG. 26), which driven member is adapted to drive acontra angle.

The collet 367 comprises a substantially cylindrical member having theexternal cylindrical surfaces 375, 376 at each end and anothercylindrical surface 377 midway between the ends with reduced portions378 and 379.

The cylindrical surfaces 375-377 fitv in the bore 360 which guides thecollet; and the collet is provided with a plurality of inwardlyextending slots 380 at each end and with an internal bore 381 at eachend, said bore having a substantial fit with the shank of a bur or othertool to be secured in the collet.

The collet actuating member 364 (FIG. 7) comprises a cylindrical membersliding in the bore 360, and having a frusto-conical cavity 382 leadingto a bore 383 for receiving the conical end 384 of the collet.

The collet has a frusto-conical end surface 385 at its outer endengaging in the frusto-conical bore 368.

The operation of the collet is as follows:

The collet bore 381 is already a substantial fit n the shank of the buror other tool. vWhen the push rod is threaded clockwise, it moves thisrod 359 to the left, pushing the collet actuating member 364, and theconical surfaces 368 and 382 cause a contraction of the ends of thecollet by engaging the outer conical surfaces 385 and 384.

The slots 380 contract and the collet resiliently grips the shank; butupon moving the rod 359 in the opposite direction, the collet springsback to non-gripping position.

The sheath 291 has its working end provided with a reduced taperedportion 386, which has a further tapered surface at 387 containing thebore 388, which houses the collet and leading to a smaller end bore 389for passing the tool shanks.

The tapered end 336 is adapted to receive the complementary taperedsocket of a contra angle or other attachment, which has a shaft thatextends into the chuck and is gripped thereby while the external housingis mounted on tapered nose 386.

The sheath 291 has its tapered nose 386 provided with a longitudinallyextending lug 390 projecting from surface 386 beyond the annularshoulder 391; and the lug 390 has a rounded end 392 and parallel edgesso that this sheath may receive the contra angle housings as previouslyconstructed. The lug 390 prevents the rotation of the housing on thesheath.

Referring to FIG. 21, this is a view in perspective of the completeassembly of the air driven straight handpiece when equipped with acontra angle for prophylaxis.

The detachable sheath extension 2911 supports a head 500, which containsa shaft 501 driving a transverse shaft 502 by means of bevel gears 503,the shaft 501 is driven from the lugs 370, 371; and the transverse shaft502 supports a rubber cup 595 used for prophylaxis.

This attachment may be employed by substituting it on the air drivenstraight handpiece for the detachable extension 291.

Referring to FIG. 22, this is an attachment carried by a similarextension 291 and having a transverse head 506 provided with, a ballbearing support shaft 507 having a plastic tube for supporting a dentalbur 508.

Referring to FIG, 23, in this case the extension 291 supports a contraangle head 512 with a driven shaft 513 for driving an amalgam packingtool 514, which is reciprocated by the drive shaft 513.

Referring to FIG. 24, this is another view showing a rotat-able shaft514 mounted in bearings in the tube 515 and carrying a grinding wheel516 protected by a shield 517. The shaft 514 is again driven by the lugs370 and 371.

Referring to FIG. 25, this is a view showing the straight handpiece whenequipped with a bur or other tool 518 held by the collet in the end ofthe straight handpiece, which is provided with a tapered collar 519carrying air nozzle 520 and the water nozzle 521 connected by flexibletubes to the air and water tubes.

Referring now to FIG. 8c, the extension 291 in FIGS. 21-24 has aninternally threaded end 451 which receives a bearing member 453 threadedinto the extension at 452. The bearing member 453 rotatably supports ashaft 459 which has a V shaped gear 479 at its end. The shaft 459supports the driven member 374 at its right end, where it is providedwith the lugs 370a and 371a.

The lugs 370a and 371a are driven by the lugs 370 on the spindle 245.

Thus the present air driven turbine may be equipped with all of theattachments shown in FIGS. 2l25, which can be driven at low speeds fordrilling, grinding, polishing, etc. The speeds may be varied from 1000to 30,000 r.p.m. by means of a knob on the air pressure regulator.

The present air driven handpiece eliminates the dental electric motor,the cord, and the engine arm, which are parts introducing extra weight,noise, and vibration.

While I have illustrated a preferred embodiment of my invention, maymodifications may be made without departing from the spirit of theinvention, and I do not wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims,

Having thus described my invention what I claim as new and desire to.secure by Letters Patent of the United States is:

1. In a dental handpiece, an air-driven turbine comprising a generallycylindrical housing having an axially-extending shaft rotatably mountedtherein, an impeller on said shaft in said housing, said impeller beingcylindrical in shape and having a multiplicity of peripheralparallelwalled slots forming radially-extending teeth, a supporting armextending radially from said housing and having a drive air conduitextend therethrough, said housing having a drive air passagecommunicating with said drive air conduit and being positioned andarranged to direct drive air tangentially against the teeth of saidimpeller, said teeth being beveled at their leading edges relative tothe direction of impeller rotation to reduce interference between suchleading edges and the air discharged into said housing and to therebyincrease the torque of said impeller, and exhaust means provided by saidhousing and arm for conveying exhaust air from said impeller, saidexhaust means including a slot extending through a side wall of saidhousing and having a radial extension in an end wall thereofcommunicating with the interior of said housing to exhaust air from oneend of said impeller as well as from the outer periphery thereof, saidexhaust means including an exhaust conduit extending through said armand communicating with said slot, said exhaust conduit terminating in anexhaust port in a peripheral groove extending about said arm, aperforated ring mounted for rotational and axial movement upon said armand normally extending over said groove, and an annular 13 replaceablefilter element disposed within said ring for absorbing oil from airdischarged through said port, and cooperating means provided by said armand ring to prevent axial displacement of said ring unless said ring isfirst rotated into a selected position of adjustment.

2. The structure of claim 1 in which said ring is provided with inwardlyextending end Walls slidably engaging the outer surface of said arm,said cooperating means comprising a pin secured to and projectingoutwardly from said arm within the confines of said ring, and a slotprovided in an end wall of said ring and alignable with said pin topermit axial movement of said ring thereover when said ring is firstrotated into a selected position of adjustment.

3. The structure of claim 1 in'which said exhaust means also includes asecond exhaust conduit extending axially through said arm andconstituting a main conduit for the discharge of exhaust air, and anexhaust passage provided by said housing and extending tangentially Withrespect to said impeller, said exhaust passage communicating with 20said exhaust conduit for the discharge of air from said housing.

References Cited by the Examiner UNITED STATES PATENTS 647,265 4/1900Hoff 253--2 1,357,609 11/1920 Bobrovsky 253-2 X 1,384,975 7/1921 Shelton3226 X 1,856,631 5/1932 Hackenberg 2532 2,073,704 3/ 1937 Mitchell 3226X 2,879,594 3/1959 Massen 3226 2,994,129 8/1961 Tanner 3227 3,059,89910/1963 Eickert 253-2 3,071,861 1/1963 Saflir 3227 3,076,267 2/ 1963Hofimeister et a1. 3226 3,120,705 1/1964 Hoifmeister et a1. -32-27FOREIGN PATENTS 837,789 5/1952 Germany.

927,151 5/ 1955 Germany.

RICHARD A, GAUDET, Primary Examiner.

ROBERT E. MORGAN, Examiner.

DELBERT B. LOWE, Assistant Examiner.

1. IN DENTAL HANDPIECE, AN AIR-DRIVEN TURBINE COMPRISING A GENERALLYCYLINDRICAL HOUSING HAVING AN AXIALLY-EXTENDING SHAFT ROTATABLY MOUNTEDTHEREIN, AN IMPELLER ON SAID SHAFT IN SAID HOUSING, SAID IMPELLER BEINGCYLINDRICAL IN SHAPE AND HAVING A MULTIPLICITY OF PERIPHERALPARALLELWALLED SLOTS FORMING RADIALLY-EXTENDING TEETH, SUPPORTING ARMEXTENDING RADIALLY FROM SAID HOUSING AND HAVING A DRIVE AIR CONDUITEXTEND THERETHROUGH SAID HOUSING HAVING A DRIVE AIR CONDUIT EXTENDTHERETHROUGH, SAID HOUSING HAVINGS DUIT AND BEING POSITIONED ANDARRANGED TO DIRECT DRIVE AIR TANGENTIALLY AGAINST THE TEETH OF SAIDIMPELLER, SAID TEETH BEING BEVELED AT THEIR LEADING EDGES RELATIVE TOTHE DIRECTION OF IMPELLER ROTATION TO REDUCE INTERFERENCE BETWEEN SUCHLEADING EDGES AND THE AIR DISCHARGED INTO SAID HOUSING AND TO THEREBYINCREASE THE TORQUE OF SAID IMPELLER, AND EXHAUST MEANS PROVIDED BY SAIDHOUSING AND ARM FOR CONVEYING EXHAUST AIR FROM SAID IMPELLER, SAIDEXHAUST MEANS INCLUDING A SLOT EXTENDING THROUGH A SIDE WALL OF SAIDHOUSING AND HAVING A RADIAL EXTENSION IN AN END WALL THEREOFCOMMUNICATING WITH THE INTERIOR OF SAID HOUSING TO EXHAUST AIR FROM ONEEND OF SAID IMPELLER AS WELL AS FROM THE OUTER PERIPHERY THEREOF, SAIDEXHAUST MEANS INCLUDING AN EXHAUST CONDUIT EXTENDING THROUGH SAID ARMAND COMMUNICATING WITH SAID SLOT, SAID EXHAUST CONDUIT TERMINATING IN ANEXHAUST PORT IN A PERIPHERAL GROOVE EXTENDING ABOUT SAID ARM, APERFORATED RING MOUNTED FOR ROTATIONAL AND AXIAL MOVEMENT UPON SAID ARMAND NORMALLY EXTENDING OVER SAID GROOVE, AND AN ANNULAR REPLACEABLEFILTER ELEMENT DISPOSED WITHIN SAID RING FOR ABSORBING OIL FROM AIRDISCHARGED THROUGH SAID PORT, AND COOPERATING MEANS PROVIDED BY SAID ARMAND RING TO PREVENT AXIAL DISPLACEMENT OF SAID RING UNLESS SAID RING ISFIRST ROTATED INTO A SELECTED POSITION OF ADJUSTMENT.